The present disclosure generally relates to biopolymers, processes for making the biopolymers, and articles of manufacturing. More particularly, the present disclosure relates to biopolymers formed from dried distillers solubles produced in the corn fermentation process.
Because of its relatively low investment and operational requirements, dry milling has become the primary method for converting starch within corn to ethanol. In the dry milling process, corn is first screened and ground to a flour. The resulting flour is combined with water and the starch within the corn is conventionally hydrolyzed into sugar by liquefaction and saccharification. The mixture is then fermented with yeast to convert the sugar into ethanol and carbon dioxide. About 30% of the mass of each kernel of corn accepted by corn ethanol producers is converted into ethanol in this manner. The output of fermentation, a mixture of ethanol, water, protein, carbohydrates, fat, minerals, solids and other unfermented components, is then distilled to boil off ethanol for recovery, purification and sale, leaving the remainder of the mixture in the bottom of the distillation stage.
The remainder at the bottom of the distillation stage is referred to as whole stillage (WS) and is typically subjected to a press or centrifugation process to separate the coarse solids from the liquid. The liquid fraction is commonly referred to as distillers solubles or thin stillage (TS). TS is frequently concentrated in an evaporator to become condensed distillers solubles (CDS), which is also commonly referred to as syrup. The coarse solids, or wet cake, collected from the centrifuge or press are known as wet distillers grains (WDG). Drying the WDG produces dried distillers grains (DDG). The WDG can be combined with the CDS to form what is commonly referred to as wet distillers grains with solubles (WDGS), which can then be dried to form dried distillers grains with solubles (DDGS). The DDG or DDGS typically has a moisture content less than 15% by weight.
In some instances, the CDS is subjected to a high temperature drying process to form dried distillers solubles, which reportedly has been used as a thermoplastic additive with a metal oxide and fiber in the preparation of extruded articles.
In other instances, the partially concentrated thin stillage or condensed distillers solubles, prior to being combined with the wet distillers grains, is subjected to a corn oil extraction process to remove at least a portion of the oil contained therein. The extracted crude corn oil can be used as a feedstock for the production of biodiesel and other products. The remaining condensed distillers solubles with at least a portion of the oil removed is then typically combined with the wet distillers grains to form WDGS and further dried as DDGS for use as animal feed. Exemplary corn oil extraction processes are disclosed in U.S. Pat. Nos. 7,601,858, 7,608,729, 8,008,516, and 8,008,517, all of which are incorporated by reference in their entireties.
The corn fermentation solids have been used to form biopolymer compositions. As noted above, the solid fraction includes the portion of solids deriving from the whole stillage. For example, U.S. Pat. No. 7,625,961 to Riebel discloses compositions that generally include the fermentation solids at 0.1 to 95% by weight and a thermoactive material at 0.1 to 95% by weight. The thermoactive material is selected to have a melting point less than the fermentation solid and generally serves as a binder in which the fermentation material can be embedded. Exemplary thermoactive materials include thermoplastics, thermoset materials, resins and the like. The fermentation solids disclosed by Riebel are generally selected from the group consisting of fermented protein solid, distiller's dried grain, distiller's dried grain-200, distiller's dried corn, distiller's dried fractionated corn, distiller's dried starch root crop, distiller's dried tuber, distiller's dried root, distiller's dried cereal grain, distiller's dried wheat, distiller's dried rye, distiller's dried rice, distiller's dried millet, distiller's dried oats, distiller's dried potato, wet cake, and solvent washed wet cake.
The liquid fraction, which contains water soluble components such as water soluble protein, may be further processed, e.g., concentration, oil extraction, and the like. The liquid fraction is then typically added back to the DDG to form DDGS, i.e., dried distillers grains with solubles.
Thus, it would be desirable for a more robust renewable material. Accordingly, it is to solving this and other needs the present disclosure is directed.